Lightning arrester



Jan. 28, 1930. Q WEICHELT 1,744,847

LIGHTNING ARRESTER Filed Feb. 16, 1928 F 7 2 3. Z 6 4. 175 5 2 5. f5?

IN V EN TOR.

Patented Jan. 28, 1930 UNITED STATES PATENT OFFICE CARL L. WEICHELT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 WIRT COM- PANY, 0F PHILADELPHIA, PENNSYL VANIA, A CORPORATION OF MAINE LIGHTNING ARRESTER Application filed February 16, 1928. Serial No. 254,724.

This invention relates to that class of de vices intended to be in conjunction with electric circuits to protect the apparatus connected in such circuits and to discharge static electricity which may accumulate from the atmosphere or result from lightning discharges.

The invention has for its main object to provide a lightning arrester in which the electrodes furnishing the air gap are in the form of a capsule so as to afford an extremely small and exact requisite spacing between these electrodes and to afford an easy means of adjustment of same in the process of manufacture thus facilitating uniformity in their electrical characteristics when produced in quantities.

Another object is to provide a lightning arrester in which the electrodes forming the airgap are constructed as a separate member or unit whereby they may be easily renewed, in case an intense static discharge breaks down the resistance.

Another object is the provision of means whereby this capsule can be easily mounted in and dismounted from a protective casing of insulating material, consisting of two members which are capable of being easily connected and disconnected.

The invention has for another object to provide easy means of mounting the capsule within the protective casing and to insure ample electrical contact between the capsule electrodes and the mounting regardless of the position of one of the members of the protective casing relative to the other, one member of the casing being capable of being screwed into the other for the purpose of uniting the parts.

Vhen an outdoor aerial is employed in operating a radio receiving circuit, a lightning arr-ester is preferably connected across the aerial to ground,'at a point between the aerial and the receiving circuit, to serve as a means of discharging static electricity which may accumulate from such sources as lightning. A general form of lightning arrester for such use is shown in the accompanying drawings; its action depends upon the tendency'of a disruptive or impulsive discharge of electricity to traverse an alternative path inc'ludingan air-gap, rather than a longer, though better conducting path, and the length of the included air gap determines the minimum voltage fromwhich the instrument will provide protection. It is essential, therefore, that the fixed air-gap in a given arrester have the proper minute value to afford the protection for which the instrument was designed. Consequently provision for an accurate setting of the fixed air-gap in an arrester is preferably included in the construction. Re ulation or adjusting of the spacing between t 1e electrodes uring the process of manufacture is also preferably provided for. Viewed from a manufacturing standpoint the means of setting and adjusting of the air-gap must be such as to provide simplicity of construction and uniformity of product.

Other general characteristics which are desirable in lightning arrester parts are compactness, ruggedness, and simplicity of construction. In addition lightning arresters, which are adapted for use in the protection of radio receiving sets, are preferably so constructed that they can be easily and permanently secured to the exterior of a building, for example, to present an appearance which is neat, orderly and in harmony with other exterior fixtures for buildings.

The present invention provides a lightning arrester which possesses the various essential characteristics outlined above and is well adapted for use across an outdoor aerial employed with a radio receiving set.

The features of the invention outlined above, together with others will be made clear with the aid of the description to be given in connection with the accompanying drawing in which like parts of the several figures are designated by similar characters of reference, and in which:

Fig. 1 is a vertical sectional view of a lightning arrester illustrating one embodiment of my invention, showing the interior assembly of the various parts;

Fig. 2 is a bottom View of the arrester;

Fig. 3 is a perspective view of the capsule casing properly forming one of the electrodes furnishing the air-gap;

perspective view of the second in Fig. 4 coaxial with the outer electrode or' casing shown in Fig 3;

Fig. 6 is a perspective view. of a thin washer of conducting material which is seated at the bottom of the outer electrode or casing and affords the spacing between the two electimid es; n

/, mem er of conducting material affording means of electrical contact between the outer electrode or casing and a circuit member within the protective casing of the arrester, as will be made apparent in the description to follow.

The lightning arrester illustrated to show a practical embodiment of m invention comprises upper and, lower tu ular members 3 and 4 preferably. composed of an insulating and water-proof material such as a molded phenol condensation product and current conductors or circuit members 6 and consisting of circular rods extending axially in opposite direction from the ends of the tubular members and rigidly secured to these members during the molding process, to which end the circuit members are provided with knurled annular ridges, as shown. Since the lightning arresters are commonly secured to the exterior of buildings and are therefore subject to the action of storms and moisture, the casing members 3 and 4 are preferably so constructed and joined as to prevent the entrance of foreign materials and particularly moisture or liquid into the enclosure. To this end,

the members 3 and 4 are each closed at one end and sealed together at their open ends by giving the upper member an internal thread and the lower member a corresponding external thread. As a further means of insuring the protection of the enclosure from moisture and particularly during stormy or inclement weather the upper member is provided with a petticoat which is formed thereon during the molding process.

The air-gap might be formed by spacing the inner adiacent ends of the conducting members 6 and 7 contiguous but this involves certain ditliculties in the process of manufact'ure particularly with respect to obtaining uniformity in the spacing between said ends which at the most are only separated a few thousandths of an inch. To accomplish this result I have determined from a practical study of the subject that much more satisfactory results can be obtained by disregarding any attempt at a close adjustment of the distance between the inner ends of the conductors and actually giving this spacing a finite distance and interposing therein an electrode unit, the parts of which can be separately assembled, and securing it in place by 7 is a perspective view of a flexible a yielding memberwhich also becomes one of the circuit conductors.

The electrodes furnishing the air-gap ma be arran ed in the form of a capsule 10 whic will furt er protect the air-gap from moisture and permit not only the requisite spacing of the air-gap but will also enable it-to be made as small as desired and at the same time afford means whereby the adj ustmentof this spacing may be accomplished during the process of manufacture.

Qne electrode consists of the cup shaped casing 13, comprising arr annular band 12 with a flat circular bottom 11. The other electrode 14 comprises a short cylinder 15 at one end of which there is a coaxial disc or head portion 16, of greater circumference. The cylinder portion 15 of this electrode fits snugly into the central opening of a washer 17 made of hard insulating material, the disc portion 16 seating snugly against one of the surfaces of the washer 17. In order to insure against displacement of the cylinder 15 from within the washer 17, these parts are cemented together and when thus secured the end surface of cylinder portion 15 is ground flush with the corresponding surface of washer 17.

A thin metallic washer 18 seated on the bottom of the electrode casing 13, forms a spacing member-and its circumference is such that it fits snugly within the wall 12. The

aperture in this spacer is centrally disposed and is of greater diameter than that of the cylindrical portion 15 of the inner electrode 14 the relative diameters of these parts being such that the distance from the rim or corner of the end of the cylinder 15 to the contiguous wall of the aperture in the spacer is the same as that between the face of the end ofthe cylinder 15 and the inner face of the bottom of the cup 13, when the parts are in assembled position. After insertion of this metallic washer 18, the insulating Washer 17 with electrode 14 inserted is then placed within the casing electrode 11 in such a manner that the flat surface of the cylinder 15 is adjacent to the flat bottom surface 11 of the casing electrode 13, these two surfaces being held apart by the metallic washer 18. It is readily seen that the air gap between the two electrodes is a function of the thickness of the metallic washer 18 and the diameter of the aperture therein and is determined substantially by these dimensions. In this way an extremely small air-gap spacing can be provided between the two electrodes. An accurate requisite spacing is also provided by making the washer of the proper desired thickness. An adjustment or regulatibn of the air gap can also be had by the use of washers of various minute thicknesses or by using several washers superposed.

The width of the annular band portion 12 of the casing electrode is slightly greater than the thickness of the insulating member 17 to tially near its open end, one of the electrodes making direct contact with the end of the circuit rod, and a flexible conducting element mounted within the upper tubular member, making contact with the end of the rod projecting into this member and affording a seat for the other electrode of the capsule, said conducting element being flexible so as to provide pressure to the capsule electrode and the rod with which it makes contact and corelated pressure between the electrode and the circuit rod within the lower tubular-member when said tubular members are joined together.

3. In a lightning arrester, two tubular insulating members, each being closed at one end, the lower member having at its open end an external thread and the upper member an internal thread so as to be joined together at their open ends, two opposed circuit rods projecting axially within each of the tubular members, a capsule element comprising two electrodes furnishing the air-gap of the arrester and mounted within the lower tubular member, the circuit rod within this member affording a seat for the capsule and making contact with one of the electrodes, and means mounted within the upper tubular member in contact with the circuit rod within the upper member and affording contact with the other capsule electrode, said means being flexible ing spacer interposed between the bottom of the cup and said washer and having a central aperture larger in diameter than the contiguous end of the second electrode, whereby the latter is spaced from the bottom of the cup shaped member and from the edge of said central aperture of said washer.

8, In a lightning arrester, the combination with a protective casing having conductors leading therein, of a renewable capsule member mountable within said casing and comprising a conducting cup shaped element serving as one electrode and having lateral sides and a bottom and a second electrode disposed therein and spaced from the bottom of said element, both of said conductors making electrical connection with said electrodes and one of said conductors affording a seat against which the bottom of said element is disposed.

This specification signed and witnessed this fourteenth day of February, 1928.

\ CARL L. WEICHELT.

so as to permanently afi'ord good electrical conduction between the circuit rods and the capsule electrodes when said tubular members are joined together.

4. A renewable electrode member for lightning arresters comprising a metallic cup shaped member having lateral sides and a bottom, said member forming one electrode, a second electrode centrally disposed therein and an insulating member supported in the cup and carrying the second electrode thereby holding said second electrode spaced from the bottom of said member.

5. A renewable electrode member for lightning arresters comprising a metallic cup shaped member having lateral sides and a bottom, said member forming one electrode, a perforated insulating washer supported by the cup and the second electrode carried by and extending through said Washer and held thereby in spaced relation to the bottom of said first electrode. v

6. A renewableelectrode member for lightning arresters comprising a metallic cup shaped member having lateral sides and a bottom, said member forming one electrode, a perforated spacer lying at said bottom, an insulating washer also provided with a perforation and fitting within the cup and overlying the spacer and a second electrode extending through the washer, thereby spaced Egrmit the free edge of the annular bandto be aded or turned inwardly as shown at 19 Fig. 1 after assembly of the parts so as to firmly secure the various parts.

One-embodimentof the means for mounting of the capsule within the casing members 3 and 4 is shown in Fig. 1. Since the circuit member 7 projects upwardly within this protective tubular member 4 for the greater portion of its height, the capsule can be readily inserted within this lower member 4, the flat surface of the disc portion 16 of the electrode 15 within the capsule seating against and making electrical contact with the flat upper surface of the circuit member 7. The diameter of the capsule 10 is only slightly less than the inside diameter of the lower tubular member 4, consequently an accurate seating of the capsule is provided and furthermorethe dimensions of the various parts are such as to make it impossible for the capsule to move laterally sufliciently to become displaced.

The other circuit member 6 projects only slightly within the upper protective tubular member 3, electrical contact being provided between its lower end and the bottom surface 11 of the capsule casing by means of a flexible'spring member 20 of conducting material which is preferably made as shown in Figure 7.

The member 20 is formed of a strip of conducting metal bent into a U shape and of suitable thickness and formed as to give the desired amount of flexibility. This band is bent substantially midway between its ends, one portion 21 being flat and the other 22 suitably curved. A circular opening 23 is provided in the flat portion 21 and part of the curved portion 22 is slotted to provide a tongue 24 which is also flexible and is located substantially between the ends 21 and 22.

In assembling the flexible member 22 within the upper protective casing 3, the inner end of the circuit member 6 is projected through the aperture 23 its extremity contacting with the tongue 24, thus providing electrical contact to this member. I deem it preferable to also surround the conductor 6 with a shoulder 25 against which the flat portion 21 may rest thus affording an area of contact that will hold the member 20 in its proper position.

With the flexible member mounted within the upper protective casing and the capsule mounted within the lower protective casing, the two parts of the casing are screwed tightly together thus placing the arms 21, 22, and 24 under tension. In this way spring portions 24 and 22 of the flexible contact member 20 make good electrical contact with the circuit member 6 and the capsule casing electrode 11 respectively. Owing to the pressure afforded by the curved spring portion 22 against the capsule casing, good electrical contact will also be established between the lower circuit member 7 and the inner electrode 14. In this way a satisfactory contact between the circuit membersfi and 7 and the capsule electrodes will at all times be maintained, regardless of the position of one of the protective members relative to the other due to a possible-loosening of the threads holding these together.

Another feature of design comprises a, flange or shoulder located on the exterior of the lower tubular member and adapted to support a bracket without danger of arcing between the instrument and the bracket durng a storm. The bracket holding the arrester 1s ailapted to be secured to a wall orother suppor These circuit members 6 and 7 carry at their outer ends binding posts or terminals 8 and 9 to which the aerial and ground leadsare connected. The instrument thus serves as an alternative path over which the usual currents of comparatively small voltage will not pass but which will be traversed readily by disruptive or impulsive discharges of electricity accumulated in any manner by the exposed wires and lead-in with which the device is associated.

I claim:

1. In a lightning arrester, the combination with two tubular insulating members closed at their opposite ends and joined at their open ends and having two opposed circuit conductors projecting axially within them, of a capsule member mounted within one of said tubular members andcomprising two electrodes furnishing the air gap of the arrester, one of said electrodes being seated on and making direct contact with that circuit conductor which projects within said member, and a conducting element mounted within the other tubular member and comprising a flat perforated prong fitting the projecting portion of the other circuit conductor and seating against the closed end of said other tubular member, a second prong affording a seat for the other electrode of the capsule and a third prong located between the other two and abutting the end of the projecting portion of said other circuit conductor, said second and third prongs being flexible so as to provide pressure to the electrode and circuit conductor with which they contact and hence co-related pressure between the electrode and the circuit conductor making direct contact, when said ing the air gap of the arrester, and mounted within the lower tubular member substan- 

